Move to push-push design for hidden threads sync with catalog.

Only changes to the list are pushed.
Fails at syncing with catalog across http/https, but fixes
the issue where changes to the list would be reverted.

src/Filtering/ThreadHiding.coffee

@@ -2,25 +2,32 @@ ThreadHiding =
   init: ->
     return if g.VIEW is 'thread' or !Conf['Thread Hiding Buttons'] and !Conf['Thread Hiding Link'] and !Conf['JSON Navigation']
     @db = new DataBoard 'hiddenThreads'
-    return @catalogHide() if g.VIEW is 'catalog'
+    return @catalogWatch() if g.VIEW is 'catalog'
+    @cleanCatalog()
     Thread.callbacks.push
       name: 'Thread Hiding'
       cb:   @node
 
-  catalogHide: ->
-    @hiddenThreads = ThreadHiding.db.get
-      boardID: g.BOARD.ID
-      defaultValue: {}
-    @hiddenThreads[threadID] = true for threadID of @hiddenThreads
-    localStorage.setItem "4chan-hide-t-#{g.BOARD}", JSON.stringify @hiddenThreads
+  getCatalogHidden: ->
+    JSON.parse(localStorage.getItem "4chan-hide-t-#{g.BOARD}") or {}
+
+  setCatalogHidden: (threads) ->
+    if Object.keys(threads).length
+      localStorage.setItem "4chan-hide-t-#{g.BOARD}", JSON.stringify threads
+    else
+      localStorage.removeItem "4chan-hide-t-#{g.BOARD}"
+
+  catalogWatch: ->
+    @hiddenThreads = ThreadHiding.getCatalogHidden()
     $.ready ->
+      # 4chan's catalog sets the style to "display: none;" when hiding or unhiding a thread.
       new MutationObserver(ThreadHiding.catalogSave).observe $.id('threads'),
         attributes: true
         subtree: true
         attributeFilter: ['style']
 
   catalogSave: ->
-    hiddenThreads2 = JSON.parse localStorage.getItem "4chan-hide-t-#{g.BOARD}"
+    hiddenThreads2 = ThreadHiding.getCatalogHidden()
     for threadID of hiddenThreads2 when !(threadID of ThreadHiding.hiddenThreads)
       ThreadHiding.db.set
         boardID:  g.BOARD.ID
@@ -30,6 +37,7 @@ ThreadHiding =
       ThreadHiding.db.delete
         boardID:  g.BOARD.ID
         threadID: threadID
+    ThreadHiding.hiddenThreads = hiddenThreads2
 
   node: ->
     if data = ThreadHiding.db.get {boardID: @board.ID, threadID: @ID}
@@ -44,6 +52,24 @@ ThreadHiding =
         ThreadHiding.makeStub thread, root
     return
 
+  cleanCatalog: ->
+    # We need to clean hidden threads on the catalog ourselves,
+    # otherwise if we don't visit the catalog regularly
+    # it will pollute the localStorage.
+
+    # Only clean the catalog if our own hidden threads list was just cleaned.
+    return unless (ThreadHiding.db.data.lastChecked or 0) > Date.now() - $.MINUTE
+
+    $.cache "//a.4cdn.org/#{g.BOARD}/threads.json", ->
+      return unless @status is 200
+      hiddenThreadsOnCatalog = ThreadHiding.getCatalogHidden()
+      threads = {}
+      for page in @response
+        for thread in page.threads
+          if thread.no of hiddenThreadsOnCatalog
+            threads[thread.no] = hiddenThreadsOnCatalog[thread.no]
+      ThreadHiding.setCatalogHidden threads
+
   menu:
     init: ->
       return if g.VIEW isnt 'index' or !Conf['Menu'] or !Conf['Thread Hiding Link']
@@ -145,15 +171,19 @@ ThreadHiding =
     $.prepend root, thread.stub
 
   saveHiddenState: (thread, makeStub) ->
+    hiddenThreadsOnCatalog = ThreadHiding.getCatalogHidden()
     if thread.isHidden
       ThreadHiding.db.set
         boardID:  thread.board.ID
         threadID: thread.ID
         val: {makeStub}
+      hiddenThreadsOnCatalog[thread] = true
     else
       ThreadHiding.db.delete
         boardID:  thread.board.ID
         threadID: thread.ID
+      delete hiddenThreadsOnCatalog[thread]
+    ThreadHiding.setCatalogHidden hiddenThreadsOnCatalog
 
   toggle: (thread) ->
     unless thread instanceof Thread

src/General/Settings.coffee

@@ -123,7 +123,10 @@ Settings =
       button.textContent = "Hidden: #{hiddenNum}"
     $.on button, 'click', ->
       @textContent = 'Hidden: 0'
-      $.delete ['hiddenThreads', 'hiddenPosts']
+      $.get 'hiddenThreads', {}, ({hiddenThreads}) ->
+        for boardID of hiddenThreads.boards
+          localStorage.removeItem "4chan-hide-t-#{boardID}"
+        $.delete ['hiddenThreads', 'hiddenPosts']
     $.after $('input[name="Stubs"]', section).parentNode.parentNode, div
   export: ->
     # Make sure to export the most recent data.